Catalyst for producing methacrylic acid

Abstract

This invention relates to a process and catalyst for producing methacrylic acid by the oxidation of methacrolein. More specifically, it relates to a process for producing methacrylic acid from methacrolein by oxidizing the same with molecular oxygen or molecular oxygen-containing gas, which is characterized by the use of a composition, as a catalyst, having a heteropolyacid structure and the general formula: Mo.sub.a V.sub.b P.sub.c Al.sub.d Y.sub.e O.sub.f wherein Mo, V, P, Al and O represent respectively molybdenum, vanadium, phosphorus, aluminum and oxygen, Y represents one or more elements selected from the groups consisting of copper, tine, cobalt, iron, zirconium, thorium, lead and cerium, and suffixes a, b, c, d, e and f represent the atomic ratio of the elements where, a is 10, b is a number of 3 or less than 3 excluding 0 and, preferably, 0.5 to 2, c is a number of 0.5 to 10 and, preferably, 0.5 to 3, d is a number of 3 or less than 3 excluding 0, preferably, 0.01 to 1.0, e is a number of 0 to 3, preferably, 0.01 to 0.5, and f is usually a number of 35 to 80 being determined depending on the valency and the ratio of number of atoms of other elements.

What is claimed is: 
     
       1. A catalyst having a heteropoly-acid structure and the general formula:   Mo.sub.a V.sub.b P.sub.c Al.sub.d Y.sub.e O.sub.f,     wherein Mo, V, P, Al and O represent respectively molybdenum, vanadium, phosphorus, aluminum and oxygen, Y represents one or more elements selected from the group consisting of copper, tin, cobalt, iron, zirconium, thorium, lead and cerium and a, b, c, d, e and f represent the atomic ratio of the elements where,   a is 10   b is a number of 3 or less than 3 excluding 0,   c is a number of 0.5 to 10,   d is a number of 3 or less than 3 excluding 0,   e is a number of 0 to 3 and   f is a number determined depending on the valency and atomic ratio of other elements.   
     
     
       2. The catalyst according to claim 1, where a is 10, b is a number of 0.5 to 2, c is a number of 0.5 to 3, d is a number of 0.01 to 1.0 and e is a number of 0.01 to 0.5. 
     
     
       3. The catalyst according to claim 1, wherein Y represents one or more elements selected from the group consisting of copper, tin, zirconium, thorium and cerium.